Tense - A set of forms taken by a verb to indicate the time (and sometimes also the continuance or completeness) of the action in relation to the time of the utterance.
Types of tenses - 1. Present tense
2. Past tense
3. Future tense
Present tense - expressing an action now going on or habitually performed or a condition now existing. Eg. I am going to a Zoo today.
Past tense - expressing an action that has happened or a state that previously existed.
Eg. I went to a Zoo yesterday.
Future tense - a tense of verbs expressing events that have not yet happened. Eg. I will be going to a Zoo tomorrow.